Meiosis and Mitosis
What is the first phase of meiosis called?
Prophase I
What process during meiosis creates genetic diversity by exchanging segments of DNA between homologous chromosomes?
Crossing over
How many chromosome pairs are found in a human gamete?
23
What is the term for a specific version of a gene?
Allele
What is the primary purpose of meiosis?
To produce haploid gametes for sexual reproduction.
During which phase of meiosis do homologous chromosomes line up in the middle of the cell?
Metaphase I
What is the term for the random alignment of homologous pairs during metaphase I?
Independent assortment
What is the term for a pair of chromosomes, one from each parent, that are similar in structure and gene content?
Homologous chromosomes
What do we call the cell formed when two gametes fuse during fertilization?
Zygote
What type of reproduction creates genetically identical offspring?
Asexual reproduction
In which phase of meiosis are sister chromatids separated into individual chromosomes?
Anaphase II
What happens during synapsis in meiosis, and how does it contribute to genetic diversity?
Synapsis is the pairing of homologous chromosomes during prophase I, allowing for crossing over, which exchanges genetic material and increases diversity.
What is the difference between haploid and diploid cells?
Haploid cells have one set of chromosomes (n), while diploid cells have two sets (2n).
What is the difference between genotype and phenotype?
Genotype refers to the genetic makeup of an organism, while phenotype refers to its observable traits.
Name one advantage of sexual reproduction over asexual reproduction.
Genetic diversity, which increases adaptability and survival.
During which stage of meiosis does crossing over occur, and why is it important?
Prophase I; it increases genetic diversity.
How does the number of chromosomes in gametes compare to that in somatic cells, and why is this important for genetic diversity?
Gametes have half the number of chromosomes (haploid) compared to somatic cells (diploid), which is crucial for maintaining chromosome number across generations and ensuring diverse combinations during fertilization.
What is the structure that holds sister chromatids together during meiosis?
Centromere
What is law of independent assortment and who invented it.
Gregor Mendel's law of independent assortment states that the alleles of two (or more) different genes get sorted into gametes independently of one another.
What is hermaphroditism, and how does it serve as an adaptive reproductive strategy?
Hermaphroditism is when an organism has both male and female reproductive organs. It can increase reproductive success by allowing self-fertilization or mating with any individual of the same species.
What are the differences in the outcome of meiosis I versus meiosis II?
Meiosis I separates homologous chromosomes, producing haploid cells with duplicated chromosomes. Meiosis II separates sister chromatids, resulting in four unique haploid gametes.
Describe how crossing over and independent assortment together contribute to evolution through natural selection.
Crossing over and independent assortment generate unique genetic combinations, increasing variation in a population. This variation provides raw material for natural selection to act upon, enhancing adaptive evolution.
How are homologous chromosomes different from sister chromatids?
Homologous chromosomes are pairs of chromosomes, one from each parent, with similar genes but potentially different alleles. Sister chromatids are identical copies of a chromosome produced during DNA replication.
How do dominant and recessive alleles affect an organism's phenotype?
A dominant allele expresses its trait even when only one copy is present, while a recessive allele expresses its trait only when two copies are present.
Why is sexual reproduction considered a better long-term strategy for species survival in changing environments compared to asexual reproduction?
Sexual reproduction generates genetic variation, enabling populations to adapt more effectively to changing environments and resist diseases, while asexual reproduction produces genetically identical offspring, making populations more vulnerable to environmental shifts.